"Don't mind me, just makin' a straw man, knocking it down..."
Chromium is entirely open source. A quick search shows that there are many bugs/mailing list posts mentioning packaged apps within the Chromium project. So the answer to your hypothetical question is: no, you're likely not right. Google may control the experience in the Chrome browser, but by providing all the code they use, you're free to implement whatever system you want on your own machine.
Parent said Chrome store, not Chrome. If apps can only be installed from the Google Play, nothing guarantees us that your homebrewed system can access them.
Well where do the apps come from? Developers. If the developers are willing to post versions of their apps that will work on Chromium in addition to Chrome Store versions, then you'll be able to use them. If they aren't then your issue is with the developer, not Google.
"Don't mind me, just makin' a straw man, knocking it down..."
Chromium is entirely open source. A quick search shows that there are many bugs/mailing list posts mentioning packaged apps within the Chromium project. So the answer to your hypothetical question is: no, you're likely not right. Google may control the experience in the Chrome browser, but by providing all the code they use, you're free to implement whatever system you want on your own machine.